It has been well established that the outer bark of most white-barked birch, such as Betula papyrifera Marsh. species, are rich in pentacyclic triterpenoid compounds, particulary betulin. Betulin and other natural triterpenoids have been extracted in good yields (20 to 30% of dry weight) from the bark of birch with organic solvents. The betulin is the major triterpenoid compound in the bark of white birches and represents about 70% of the total triterpene.
The major interest in betulin lies in the fact that it is a synthetic precursor of triterpenoid compounds having important pharmacological properties. To obtain these triterpenoid compounds, betulin must be subjected to some chemical reactions. This approach involves a step of purification of the extracted betulin and one or more steps of chemical reactions to produce the desired compound. These reactions are often non-quantitative (yield inferior to 100%) and an additional step of purification is necessary after each chemical reaction. This approach generally provides a low yield of triterpenoid compounds.